Conditional access (CA) refers generally to a technology used to control access to communicated services such as television programming. Several different CA schemes currently exist. The transmissions conveying such communicated services are typically scrambled or encrypted, and only authorized users are provided with means to descramble or decrypt the transmissions. Scrambling typically involves modifying a transmission signal by, for example, removing synchronization pulses. Encryption typically involves modifying digital data conveyed by the transmission signal according to a particular cryptographic algorithm. Conditional access has been used for many years to provide exclusive access to premium television channels and special broadcasts (e.g., sporting events and pay-per-view movies). Conditional access can also be used to provide exclusive access to digital radio broadcasts, digital data broadcasts, and interactive services. Known CA technologies for scrambling or encrypting television transmissions include VideoCrypt™ (Thomson Consumer Electronics, S A FR), VideoCipher® and DigiCipher® (NextLevel Systems, Inc., Chicago, Ill.).
A typical CA system is used to scramble or encrypt television programming, and generally includes CA encoding equipment integrated into broadcast equipment (e.g., cable, satellite, or terrestrial broadcast equipment) at a service provider's location. In general, the CA encoding equipment modifies (i.e., scrambles or encrypts) information conveyed by a transmission signal produced by the broadcast equipment. Where the CA encoding equipment employs encryption, the CA encoding equipment encrypts digital data (e.g., digitized video and audio information), and the broadcast equipment transmits a signal conveying the encrypted digital data to the subscribers. The CA encoding equipment may also insert messages into the transmission signal that provide information necessary for decryption of the encrypted digital data.
The typical CA system also includes CA decoding equipment at each subscriber's location. The CA decoding equipment typically includes a box receiving the transmission signal capable of being coupled to a television set or other display means. Such boxes are commonly referred to as “set-top boxes” or integrated receiver decoders (IRDs). A typical IRD decrypts the encrypted digital data in the transmission signal, converts the digital data to analog signals (e.g., analog video and audio signals), and provides the analog signals for display on a television set or other display means.
Messages that provide information necessary for decryption of the encrypted digital data are typically passed to a security module within an IRD. The security module extracts the information from the messages, and uses the information to authorize the decryption of the encrypted digital data. The security module is usually in the form of a “smart card.” In general, a smart card is a plastic card about the size of a credit card that has a signal processing integrated circuit (IC) embedded therein. A smart card is typically inserted into a card reader of the IRD that couples signals between the IRD and the smart card.
The IC in the smart card processes the information necessary for decryption of the encrypted digital data in the transmission signal. For example, the IC in the smart card may use the information to generate a decryption key, and provide the decryption key to a decoder within the IRD. The decoder may use the decryption key to decrypt the encrypted digital data, thereby reproducing the digital data (e.g., digital video and audio data). The IRD may convert the digital video and audio data to analog video and audio signals, respectively, and provide the analog signals to the television set for display.
Many subscribers have several television sets in their dwellings, and want conditional access services available at two or more of the television sets. In this situation, a subscriber typically has 2 options: (i) use a single IRD to select programming and provide the selected programming to the other television sets, or (ii) have multiple IRDs, one for each television set, so that different programming can be selected at each of the television sets.
Subscribers that opt for the multiple IRD option often balk at having to pay the full rate for the multiple required smart cards—one for each IRD. For this reason, conditional access service providers generally offer subscribers one smart card at a full rate and additional smart cards at a reduced rate. This creates several problems for the conditional access service provider. First and foremost, one or more of the IRDs may be removed from the dwelling and installed in another dwelling without the service provider's knowledge. In this situation, the inhabitants of the other dwelling essentially gain the benefit of the conditional access services without the service provider receiving the full rate.
In addition, there are security issues with providing multiple authentication devices to a subscriber. For example, if the multiple smart cards are provided to the subscriber through the mail, that item of mail may become lost or intercepted. In this situation, multiple instances of unauthorized usage of the services may occur until the problem is discovered and the devices are invalidated within the network.